Is there a way to display text if Cydia is installed?

I am making a mobile website and I want to know if there is a possible way to write text on the page if Cydia is i开发者_JS百科nstalled? Preferably in Javascript. I'm guessing it would be a variable and an if/else statement.

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You can test if the page is opened inside Cydia, but it not if Cydia is installed.

You can do this with matching the useragent string with Cydia.

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Well this might be possible, but I'm not sure if someone could make it.

But you can open it with a link to cydia://.

If you can check that the link is valid or something, thare might be a way.